1. Field of the Invention
The present invention relates to a device for the automatic engagement of the feed movement and of the return movement of the slide of a boring head.
2. Description of Related Art
In machine tools, boring heads and facing heads are used, which consist essentially of a displaceable tool slide which accommodates the tool for the chip removal.
The description of a boring head or a facing head for a known boring head of the U-MATIC construction type, which is manufactured by the assignee, can be obtained from the "Operating instructions" from 1988 which relate to boring heads of the types U70, U95 and U125. In this exemplary embodiment, only a feed movement can be carried out by the tool accommodating slide. After the end stop for limiting the feed movement of the tool has been reached, the return movement of the slide must be initiated by the use of a key. In this connection the key is inserted into a recess of an operating device of the boring head in order to bring about, by means of a rotary movement of the device, the return movement of the tool slide. For this reversal process, interruption of the rotary movement of the boring and facing head is unavoidable.
It is obvious that the known boring head cannot be used in modern machining centres, as with these machine tools there is no possibility of engaging by manual operation a return movement of the slide.
From a WOHLHAUPTER brochure, "Machining applications using the APD automatic facing head", publication number 120382, a further boring and facing head has become known. In this known head it is possible to automatically trigger a feed movement and a return movement of the radial slide. The known head has a projecting arm which is provided with a connection coupling which must be brought into work connection with a special connection point provided to this end on the machine tool. By these means the transfer of an air impulse becomes possible, in order to bring about the necessary control processes for the reversal of the direction of movement of the tool slide .of the boring head.
The disadvantage of this known boring head is that, in addition to a connection point in the body of the machine tool, which connection point must be connected to a compressed air source, precise control of the compressed air impulse must also be carried out, in order to thus initiate the reversal of the direction of movement of the tool slide at a desired point.
From U.S. Pat. No. 4,637,285 a further boring and facing head has become known, which has an automatic device for the control of the feed movement and of the return movement of the slide. This head not only has an extraordinarily expensive mechanical construction, but there are also operating means, for the control of the movement of the tool slide, provided on the outside of the head. Furthermore, it is not possible with this known device to carry out a boring process with continuous feed movement. In the described exemplary embodiment according to U.S. Pat. No. 4,637,285, the feed of the tool is carried out in steps, and so the tool is, for example, indexed to the next position after four revolutions.